Planetary gear mechanism having means for accurate alignment of sun gear

ABSTRACT

A planetary gear mechanism including a rotating shaft having a splined end portion, a sun gear splined at a free end of the splined end portion, planetary gears engaging the sun gear, a carrier for rotatably supporting the planetary gears, a ring gear engaging the planetary gears, a clutch for connecting the rotating shaft and the carrier. The clutch has a first rotary member splined on the splined end portion of the rotating shaft such that the first rotary member is adjacent to the sun gear at the free end of the shaft, a first friction member rotatable with the first rotary member, a second rotary member rotatable with the carrier, and a second friction member rotatable with the second rotary member. The first and second friction member frictionally engage each other to transmit power therebetween. The first rotatary member is rotatably supported by a housing of the mechanism, and the sun gear axially slidably engages the first rotary member, for coaxial relation with the first rotary member, whereby the sun gear is maintained in coaxial relation with the nominal axis of rotation of the rotating shaft.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a planetary gear mechanism whereinplanetary gears are efficiently lubricated.

2. Discussion of the Prior Art

A power transmission incorporating a planetary gear mechanism is known.Such a planetary gear transmission is widely used for motor vehicles andindustrial machines and equipment. In particular, the planetary geartransmission is most commonly used as an automatic transmission formotor vehicles, owing to its comparatively high degree of smoothness inchanging the speed reduction ratio during power transmission, and itscomparatively small size. Further, a planetary gear mechanism is used asan auxiliary transmission coupled to a continuously variabletransmission, as disclosed in laid-open Publications 60-252857 and61-130656.

For example, the planetary gear mechanism of a planetary geartransmission includes a rotating shaft having a splined end portion, asun gear splined at the free end of the splined end portion such thatthe sun gear is rotatable with the rotary shaft, a carrier rotatablysupporting planetary gears which engage the sun gear, a ring gearengaging the planetary gears, and a clutch disposed between the rotatingshaft and the carrier, for transmitting power between the rotating shaftand the carrier.

In the planetary gear mechanism constructed as indicated above, theclutch for connecting the rotating shaft and the carrier generally usesfirst friction means which is supported by a first rotary memberrotating with the rotating shaft, and second friction means which issupported by a second rotary member rotating with the carrier. The firstand second friction means are adapted to frictionally engage with eachother for transmitting power between the first and second rotarymembers, i.e., between the rotating shaft and the carrier The firstrotary member is also splined on the rotating shaft such that the firstrotary member is adjacent to the sun gear at the free end of the splinedportion of the rotating shaft.

Usually, there exists a certain amount of clearance between the splinesof the splined end portion of the rotating shaft and the spline groovesof the sun gear. Therefore, the rotating shaft and the sun gear more orless suffer from an error in concentricity or a radial playtherebetween, which causes various problems. For instance, the carriercannot be precisely aligned with the sun gear, due to misalignment ofthe sun gear which arises from the above-indicated clearance. Usually,the first rotary member and the sun gear are first splined on thesplined end portion of the rotating shaft. Then, the carrier isassembled to the sun gear, through a thrust bearing interposedtherebetween, such that one of opposite axially extending annularretainer portions of the thrust bearing engages the boss or cylindricalportion of the carrier, while the other annular retainer portion engagesthe sun gear. If the sun gear is not accurately aligned with the axis ofrotation of the rotating shaft, the thrust bearing which has beenattached at one of its annular retainer portions to one of the sun gearand the carrier cannot be easily brought into engagement with the otherof the sun gear and the carrier.

On the other hand, the radial clearance between the splines of thesplined end portion of the rotating shaft and the spline grooves of thefirst rotary member and sun gear may be used as a passage for feeding alubricant toward the free end of the rotating shaft. In this case, thelubricant may leak through a gap between the first rotary member and thesun gear, and the thrust bearing cannot be sufficiently lubricated.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide aplanetary gear mechanism wherein the sun gear of the planetary gearmechanism is accurately aligned coaxially with the nominal axis ofrotation of the rotating shaft.

The above object may be achieved according to the principle of thepresent invention, which provides a planetary gear mechanism comprising:a rotating shaft having a splined end portion; a sun gear splined at afree end of the splined end portion, for rotation with the rotatingshaft; planetary gears engaging the sun gear; a carrier for rotatablysupporting the planetary gears; a ring gear engaging the planetarygears; a clutch for connecting the rotating shaft and the carrier, theclutch including a first rotary member splined on the splined endportion of the rotating shaft, for rotation with the rotating shaft suchthat the first rotary member is adjacent to the sun gear at the freeend, first friction means supported by and rotatable with the firstrotary member, a second rotary member rotatable with the carrier, andsecond friction means supported by and rotatable with the second rotarymember, the first and second friction means frictionally engaging eachother to transmit power therebetween; a housing in which the firstrotary member, the sun gear, the planetary gears, the carrier, the ringgear and the clutch are accommodated, the housing rotatably supportingthe rotating shaft; and the first rotary member and said sun gearaxially slidably engaging each other, for coaxial relation with eachother.

In the planetary gear mechanism of the present invention constructed asdescribed above, the first rotary member which is rotated with therotating shaft is rotatably supported by the housing, with accuratecoaxial relation with the nominal axis of rotation of the rotatingshaft. Since the sun gear axially slidably engages the thus accuratelyaligned first rotary member, the sun gear is supported by the housingvia the first rotary member, with a high degree of radial alignment withrespect to the nominal axis of rotation of the rotating shaft. Thisarrangement facilitates assembling of the carrier of the clutch withrespect to the sun gear which is splined at the free end of the splinedend portion of the rotating shaft. Usually, the first rotary member andthe sun gear are first splined on the splined end portion of therotating shaft, and the carrier is connected to the sun gear. Since thesun gear has a high degree of concentricity with the nominal axis ofrotation of the carrier, the carrier may be easily assembled in precisecoaxial alignment with the sun gear.

Usually, a thrust bearing is interposed between the cylindrical portionor boss of the carrier and the end of the sun gear. In this case, thethrust bearing has opposite annular retainer portions which extends inaxially opposite directions for engagement with the boss of the carrierand the bore of the sun gear. The appropriate one of the annularretainer portions of the thrust bearing may be readily fitted in thebore of the sun gear or the carrier boss, owing to the accurate radialalignment of the sun gear with respect to the housing, i.e., withrespect to the nominal axis of rotation of the rotating shaft and thecarrier.

In one form of the present invention, the first rotary member includes afirst annular extension which axially extends from one of opposite axialends thereof toward the sun gear, and the sun gear includes a secondannular extension which axially extends from one of opposite axial endsthereof toward the first rotary member. The first and second annularextensions axially slidably engage each other, to assure precise coaxialrelationship of the sun gear with the first rotary member.

In another form of the invention, the first rotary member and the sungear cooperate with the splined end portion of the rotating shaft, todefine therebetween a radial clearance which extends axially of therotating shaft and whose amount is sufficient to permit a lubricant toflow therethrough. In this case, the engagement of the first rotarymember and the sun gear results in reducing the amount of leakage of thelubricant from the interface of the first rotary member and the sungear. Preferably, the first rotary member and the sun gear are held influid-tight slidable contact with each other.

Where the thrust bearing as indicated above is provided between thecarrier and the sun gear, the bearing is suitably lubricated by thelubricant which is supplied through the radial clearance between thesplined end portion of the rotating shaft, and the first rotary memberand sun gear.

The first rotary member may comprise a connecting member splined on thesplined end portion of the rotating shaft, and a clutch drum secured tothe connecting member for rotation therewith, the first friction meansbeing supported by the clutch drum.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be better understood by reading the following detaileddescription of presently preferred embodiments of the invention, whenconsidered in connection with the accompanying drawings, in which:

FIG. 1 is a schematic view of a power transmitting system of a motorvehicle incorporating one embodiment of a planetary gear transmission ofthe present invention;

FIG. 2 is an elevational view in cross section of the planetary geartransmission of FIG. 1, taken along line II--II of FIG. 4;

FIG. 3 is an elevational cross sectional view showing in enlargement anauxiliary transmission in the planetary gear transmission;

FIG. 4 is a schematic elevational view of the planetary geartransmission as seen in the axial direction, showing a generalarrangement of some elements of the system; and

FIGS. 5 and 6 are fragmentary views illustrating other embodiments ofthe invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to the schematic view of FIG. 1, the power transmittingsystem adapted for use on a transverse FF (front-engine, front-drive)vehicle incorporates a planetary gear transmission constructed accordingto one embodiment of the present invention. The system is disposed in atransaxle housing of the vehicle. In FIG. 1, reference numeral 8 denotesan engine whose power is transmitted to drive wheels 21, 21, through afluid coupling 10 equipped with a lock-up clutch, a belt-and-pulley typecontinuously variable transmission 12 (hereinafter abbreviated as "CVT12"), an auxiliary transmission 14, a reduction gear device 16, adifferential gear device 18, and drive axles 20, 20 to which the drivewheels 21 are connected.

The fluid coupling 10 has a pump impeller 24 fixed to a crankshaft 22 ofthe engine 8, a turbine impeller 28 fixed to an input shaft 26 of theCVT 12, a damper 30 fixed to the input shaft 26, and the above-indicatedlock-up clutch 32 connected to the input shaft 26 through the damper 30.The turbine impeller 28 is driven such that rotation of the pumpimpeller 24 is imparted to the turbine impeller 28 by means of an oilbetween the two impellers 24, 28. The lock-up clutch 32 is activated orengaged for direct connection of the crankshaft 22 to the input shaft 26of the CVT 12, when the running speed of the vehicle or the rotatingspeed of the turbine impeller 28, for example, exceeds a preset upperlimit.

The CVT 12 includes a first variable-diameter pulley 36 mounted on theinput shaft 26, a second variable-diameter pulley 38 mounted on anoutput shaft 34, and a transmission belt 40 which connects the twopulleys 36, 38. The first pulley 36 has a stationary rotor 42 fixed tothe input shaft 26, and an axially movable rotor 46 provided on theinput shaft 26 such that the rotor 46 is axially movable relative to theinput shaft 26. Similarly, the second pulley 38 has a stationary rotor44 fixed to the output shaft 34, and an axially movable rotor 48 axiallymovably provided on the output shaft 34. The axially movable rotors 46and 48 are rotated with the input and output shafts 26, 34,respectively, and are axially moved by respective hydraulic actuators inthe form of hydraulic cylinders 50, 52. The stationary and movablerotors 42, 46, and the stationary and movable rotors 44, 48 defineV-grooves of the pulleys 36, 38 whose effective widths are varied as themovable rotors 46, 48 are axially moved. In other words, the effectivediameters of the pulleys 36, 38 which engage the transmission belt 40are changed with axial movements of the movable rotors 46, 48 relativeto the stationary rotors 42, 44, whereby the speed ratio "r" of the CVT12 is accordingly changed. In the present embodiment, the speed ratio"r" is equal to Nin/Nout, where Nin and Nout represent the rotatingspeeds of the input and output shafts 26 and 34, respectively. Thehydraulic cylinder 50 for the first pulley 36 is a so-called"double-piston" type cylinder, and is activated primarily for changingthe speed ration "r". The hydraulic cylinder 52 for the second pulley 38is activated primarily for establishing an optimum tension of thetransmission belt 40 such that the belt tension or a force of the beltacting on each pulley 36, 38 is held to a required minimum fortransmitting torque between the two pulleys without a slip of the belt40 on the pulleys.

Reference numeral 54 in FIG. 1 designates a hydraulic pump whichconstitutes a hydraulic power source of a hydraulic system (not shown,and not essential to the understanding of the present invention) forcontrolling the CVT 12 and auxiliary transmission 14. The hydraulic pump54 is driven with the pump impeller 24, which is rotated as long as theengine 8 is operated. Examples of the hydraulic system for the CVT 12and auxiliary transmission 14 are disclosed in toto or in part inlaid-open Publication Nos. 62-9055 and 62-196445 of unexamined JapanesePatent Applications, and in Japanese Patent Application No. 62-208781.

The auxiliary transmission 14, which is connected in series andcoaxially with the output shaft 34 of the CVT 12, incorporates adouble-pinion type planetary gear mechanism which has a forward driveposition and reverse a drive position which are selectively,established, in response to operations of a shift lever to theappropriate positions. The planetary gear mechanism or auxiliarytransmission 14 includes: a sun gear 56 disposed integrally with theoutput shaft 34; a ring gear 58 disposed coaxially with the sun gear 56;a plurality of pairs of planetary gears, each pair consisting of twoplanetary gears 60, 62 which mesh with each other and mesh with the ringand sun gears 58, 56, respectively; and a carrier 70 which has a boss 64coaxial with the sun and ring gears 56, 58, a flange 66 extendingradially outwardly from the boss 64, and carrier pins 68 which extendfrom the flange 66 in the axial direction of the boss 64, for rotatablysupporting the planetary gears 60, 62.

The planetary gear mechanism 14 further includes a forward clutch 72 forconnecting the stationary rotor 44 of the second pulley 38 and thecarrier 70 when required, and a reverse brake 76 for connecting the ringgear 58 and a stationary housing 74 when required. With the forwardclutch 72 engaged, the stationary rotor 44 and the carrier 70 areconnected so that the carrier 70 is rotated with the output shaft 34 ofthe CVT 12, whereby a first gear 78 coaxially fixed to the boss 64 ofthe carrier 70 is rotated in a forward direction for running the vehicleforward. When the reverse brake 76 is engaged, on the other hand, thering gear 58 is connected to the stationary housing 74 so that the ringgear 58 is held stationary, whereby the carrier 70 and the first gear 78are rotated in a reverse direction opposite to the direction of rotationof the output shaft 34, for running the vehicle backward. The first gear78 functions as an output gear of the auxiliary transmission orplanetary gear mechanism 14.

The first gear 78 also functions as part of the reduction gear device16. This device 16 further includes a second gear 80 and a third gear 82which are connected to each other for rotation as a unit, by a rotatablysupported shaft parallel to the axis of the first gear 78. The secondgear 80 has an externally toothed portion 80a which meshes with anexternally toothed portion 78a of the first gear 78, and has a largerdiameter than the first gear 78. The third gear 82 has a diametersmaller than the second gear 80, and meshes with a large-diameter gear84 of the differential gear device 18.

The differential gear device 18 includes a pair of small differentialgears 86 which are rotated with the large-diameter gear 84, and a pairof large differential gears 88 which mesh with the small differentialgears 86 and are fixed to the drive axles 20. In this arrangement, powertransmitted from the auxiliary transmission 14 is distributed by thedifferential gear device 18, evenly to the left and right drive axles 20and to the corresponding left and right drive wheels 21.

Referring next to FIG. 2, the power transmitting system schematicallyshown in FIG. 1 will be described in more detail. The housing 74 is analuminum die-casting, for example, and consists of a first casing 74a, asecond casing 74b and a third casing 74c, which are integrally assembledby bolts. Within the housing 74, there are defined a first chamber 90for accommodating the fluid coupling 10, a second chamber 92 foraccommodating the CVT 12, a third chamber 94 for accommodating theauxiliary transmission or planetary gear device 14, and a fourth chamber96 for accommodating the reduction gear device 16 and the differentialgear device 18. The first and second casings 74a, 74b are secured toeach other by bolts 98.

The hydraulic pump 54 has a rotor 100 in the form of a gear which ismounted on a cylindrical portion of the pump impeller 24 such that therotor 100 is rotatable relative to and eccentric with the cylindricalportion The pump 54 further has a pump casing 102 which has internallyformed teeth engaging the rotor 100. The casing 102 is fitted in a hole103 which is formed through a wall of the first casing 74a whichseparates the first and second chambers 90, 92. The casing 102 issecured by bolts 104 to the second casing 74b.

The second casing 74b has an opening 106 formed therein. A valve body108 is fixed by bolts 112 to the portion of the second casing 74b whichdefines the opening 106. The valve body 108 incorporates therein valvesfor controlling the forward clutch 72 and the reverse brake 76, andsupports an accumulator 110 fixed thereto by bolts 107. The valve body108 is positioned such that the accumulator 110 is accommodated in thesecond chamber 92. The accumulator 110 has a cylindrical body 114 whichis closed at its one end and open at the other end, and includes apiston 116 slidably received within the body 114, and a spring 118 whichbiases the piston 116 in a direction that causes a variable volume ofthe accumulator to decrease. To one of opposite surfaces of the valvebody 108, there is fixed by bolts 111 a valve plate 109 which has fluidpassages. The valve plate 109 is covered by a cover 113 which is fixedto the second casing 74b by the bolts 112 used for fixing the valve body108.

The accumulator 110 is connected to a hydraulic actuator for driving theforward clutch 72 and reverse brake 76. A variation in the volume of theaccumulator 110 contributes to mitigation of a rate of rise of the fluidpressure supplied from the control valves indicated above, therebyfacilitating the engaging actions of the clutch 72 and brake 76. Sincethe accumulator 110 is a component separate from the second casing 74b,the casing 74b does not suffer from undesirable blow holes which mightbe formed if the accumulator was formed as an integral part of thesecond casing 74b. Thus, the second casing 74b is not rejected as anunacceptable part due to such blow holes, and is constructed withcomparatively simple configuration and reduced weight. If the die-castcasing 74b had an integrally formed accumulator portion, thisaccumulator portion should be formed with a relatively large thickness.Further, the separate accumulator 110 can be removed from the secondcasing 74b, and can be inspected as a separate part. Moreover, theworkpiece for the accumulator 110 can be relatively easily machined forforming a bore in which the piston 116 is received. If the accumulatorwas provided as an integral part of the cast second casing 74b, theworkpiece for the casing 74b should be machined at an exclusive workingstation for boring the accumulator portion.

The input shaft 26 of the CVT 12 is rotatably supported by two bearings120, 122 fixed to the respective second and third casings 74b, 74c, suchthat the input shaft 26 is coaxial with the crankshaft 22. The outputshaft 34 of the CVT 12 is rotatably supported by two bearings 124, 126also fixed to the second and third casings 74b, 74c, such that theoutput shaft 34 is parallel to the input shaft 26.

To the first casing 74a, there is fixed a fourth casing 74d whichsupports the second and third gears 80, 82. This fourth casing 74dseparates the third and fourth chambers 94, 96 from each other. Theshaft portion of the first gear 78 is supported by two bearings 128 and130 fixed to the fourth casing 74d, such that the first gear 78 isrotatable about an axis coaxial with the output shaft 34. The second andthird gears 80, 82 have a common shaft portion which is supported bybearings 132, 134, such that the gears 80, 82 are rotatable about anaxis parallel to the axis of the first gear 78. The first and secondcasings 74a, 74b have bearings 138, 140 fixed thereto, which rotatablysupport a differential casing 136 to which the large-diameter gear 84 issecured. The differential casing 136 has a pin which rotatably supportsthe small differential gears 86.

The first casing 74a is formed with a portion having a circumferentialwall 144, and a lubricant passage 146 which terminates in the wall 144.The circumferential wall 144 extends in the fourth chamber 96, so as tosurround a lower part of the periphery of a portion of the second gear80 on the side of the differential gear device 18. The circumferentialwall 144 is adapted to receive a lubricant, which is once pumped up fromthe bottom portion of the fourth chamber 96 by rotation of the gears 84,82, 80. The lubricant received by the circumferential wall 144 isdirected through the lubricant passage 146 to the bearing 138 for thedifferential casing 136, so that the bearing 138 which is subject to ahigh load is suitably lubricated. The second casing 74b also has anotherlubricant passage 147 which communicates with the bearing 140. Thispassage 147 is adapted to receive the lubricant which falls along theinner surface of the wall of the fourth chamber 96 to which the bearing140 is secured. Thus, the bearing 140 is effectively lubricated.

Referring next to FIG. 3, the auxiliary transmission 14 and thereduction gear device 16 will be described in greater detail. The endsection of the output shaft 34 (i.e., input shaft of the auxiliarytransmission 14) which extends through the second casing 74b into thethird chamber 94 includes a splined portion 148 which has a smalldiameter and a plurality of circumferentially spaced-apart spline teeth.A connecting member 152 and the sun gear 56 are splined to the splinedportion 148 of the input shaft 34 of the transmission 14. To theconnecting member 152 is integrally secured a cylinder body 150 whichhas an annular cylinder bore slidably receiving an annular piston 154.The cylinder body 150, piston 154, and a return spring 155 for biasingthe piston 154 constitute a hydraulic actuator for activating theforward clutch 72.

The forward clutch 72 includes a plurality of plates 157 which engagethe radially outer circumferential wall of the cylinder body or clutchdrum 150, such that the plates 157 are accommodated within the drum 150and rotated with the drum 150. These plates 157 are axially movablerelative to the drum 150 and are spaced apart from each other in theaxial direction. The clutch 72 further includes a plurality of discs 161which engage a clutch hub 159 secured to a portion of the carrier 70.The discs 161 are rotated with the clutch hub 159 and axially movablerelative to the hub. The plates 157 and the discs 161 are alternatelyarranged such that each disc 161 is positioned between the two adjacentplates 157. A rotary movement of the clutch drum or cylinder body 150 isimparted to the carrier 70 by pressing contact of the plates and discs157, 161 with each other by an advancing movement of the piston 154against the biasing action of the return spring 155.

A sleeve 158 is press-fitted in a bore 156 of the second casing 74bthrough which the input shaft 34 of the auxiliary transmission 14extends into the third chamber 94. The connecting member 152 indicatedabove is supported by the second casing 74b through the sleeve 158, anda bearing 160 interposed between the sleeve 158 and the connectingmember 152. The portion of the second casing 74b through which the bore156 is formed functions as a wall for supporting the input shaft 34 ofthe transmission 14 (output shaft of the CVT 12). Since the assembly ofthe cylinder body 150 and connecting member 152 is rotatably supportedby the second casing 74b through the bearing 160 interposed between theouter surface of the connecting member 152 and the inner surface of thesleeve 158, the cylinder body 150 is held in concentric or coaxialrelation with the bore 156 with a high degree of accuracy. Further,there is provided a considerably large amount of clearance between thesplines of the splined portion 148 and the spline grooves of theconnecting member 152 and sun gear 56. This large clearance permits thecylinder body 150 (and the connecting member 152) and the sun gear 56 toremain highly concentric with the bore 156, even if the input shaft 34is deflected or flexed due to the tension of the transmission belt 40.Namely, the misalignment of the splined portion 148 due to thedeflection of the input shaft 34 is less likely to influence theconcentricity of the connecting member 152 and sun gear 56 with respectto the bore 156 of the second casing 74b. If the bearing 160 was notprovided and the splined portion 148 was splined to the connectingmember 152 and sun gear 56 with a relatively small amount of clearancefor required relative concentricity of these elements, as in aconventional arrangement, the deflection of the input shaft 34 mayinfluence the concentricity of the elements 150, 152, 56 with the bore156, causing operating noises of the auxiliary transmission 14 andshortening the life expectancy of the transmission, particularly wherethe transmission operates at a high speed under a high load.

Between the outer surface of a portion of the sleeve 158 and the innersurface of the bore 156, there is formed a supply passage 162 forsupplying a pressurized fluid to the pressure chamber defined betweenthe cylinder body 150 and the piston 154. The sleeve 158 has athrough-hole 166 which forms a part of a lubricant passage 164 forforce-lubricating the splined portion 148 of the input shaft 34. Thislubricant passage 164 is formed to receive a portion of the pressurizedfluid produced by the hydraulic pump 54, for example, a portion of thefluid whose pressure is regulated for operating the lock-up clutch 32 ofthe fluid coupling 10.

The piston 154 of the hydraulic actuator 150, 154, 155 for activatingthe forward clutch 72 is provided with a check valve 168 which inhibitsa discharge flow of the fluid from the pressure chamber when thepressure in the pressure chamber is high, but permits the discharge flowwhen the pressure is lowered to disengage the forward clutch 72. Thus,the check valve 168 assures an improved disengaging action of the clutch72.

The sun gear 56 is splined to the end portion of the splined portion 148of the input shaft 34 of the transmission 14, such that the opposed endsof the sun gear 56 and the connecting member 152 engage each other.Described more specifically, the connecting member 152 has an annularextension 170 axially extending toward the sun gear 56, while the sungear 56 has an annular extension 172 axially extending toward theconnecting member 152. These annular extensions 170 and 172fluid-tightly engage each other such that the sun gear 56 and theconnecting member 152 are axially slidable relative to each other.According to this arrangement, the sun gear 56 can be aligned coaxiallywith the connecting member 152 with high precision. In other words, thesun gear 56 can be accurately aligned with the bore 156 of the secondcasing 74b, through the connecting member 152 and the bearing 160.Consequently, the input shaft 34, connecting member 152, sun gear 56,carrier 70 and thrust bearing 174 may be easily assembled.

Described more particularly, the connecting member 152 and the suns gear56 are first splined onto the splined portion 148 of the input shaft 34.Then, the carrier 70 is coaxially connected to the sun gear 56 splinedat the end of the splined portion 148. As indicated in FIG. 3, thethrust bearing 174 has axially opposite annular retainer portions, oneof which engages the bore of the boss 64 of the carrier 70, while theother of which engages the bore of the sun gear 56. When the carrier 70with the thrust bearing 174 attached thereto is assembled with the sungear 56, the annular retainer portion of the thrust bearing 174 can beeasily fitted in the bore of the suns gear 56, since the suns gear 56 isaccurately aligned with the connecting member 152, which in turn isaccurately aligned with the bore 156 of the second casing 74b. Thus, themutual engagement of the annular extensions 170, 172 of the connectingmember 152 and sun gear 56 assures precise concentric or coaxialrelationship between the sun gear 56 and the carrier 70 (thrust bearing174), when these members are assembled together.

Further, since the annular extensions 170, 172 are held in fluid-tight,axially slidable contact with each other, the lubricant which issupplied through the through-hole 166 to the splined portion 148 insidethe sleeve 158 can be fed to the sun gear 56, through the relativelylarge clearances between the splines and spline grooves of the splinedportion 148 and the connecting member 152 that loosely engage eachother. If necessary, part of the splines of the splined portion 148 maybe removed to permit a sufficient flow of the lubricant between thesplined portion 148 and the connecting member 152 and sun gear 56. Thelubricant fed in between the sun gear 56 and the splined portion 148 isthen fed radially outwardly, through the bearing 174 between the sungear 56 and the boss 64 of the carrier 70. Thus, not only the splinedportion 148 and the associated members, but also the planetary gears 60,62, ring gear 58, reverse brake 76 and other members which are disposedradially outwardly of the sun gear 56 may be suitably lubricated.

The connecting member 152 has a hole 175, so that the lubricant which ispassed through the bearing 160 and the clearance between the sleeve 158and the connecting member 152 may be fed through the hole 175 anddelivered by a centrifugal force in the radially outward direction, tothereby lubricate the forward clutch 72. The annular extension 172 ofthe sun gear 56 has a hole 177 which permit the lubricant to bedelivered to the plates 157 and discs 161 of the forward clutch 72, andthe other members 14. Further, the lubricant fed radially inwardlythrough the through-hole 166 may be delivered through the clearancebetween the input shaft 34 and the sleeve 158, to lubricate the bearing126 which is operated under a high load while supporting the input shaft34.

The output gear 78 of the auxiliary transmission 14, namely, the firstgear 78 of the reduction gear device 16 has a shaft portion whose end isheld in fluid-tight engagement with the end of the input shaft 34a ofthe transmission 14. The input shaft 34 and the shaft portion of theoutput gear 78 has a fluid passage 176 formed therethrough for supplyingthe pressurized fluid to the hydraulic cylinder 52. The shaft portion ofthe output gear 78 also has a splined portion 178 to which the boss 64of the carrier 70 is splined. As previously described, the flange 66which extends radially outwardly from the cylindrical boss 64 has thecarrier pins 68 secured thereto. The carrier pins 68 rotatably supportthe planetary gears 60, 62 through a needle bearing 180. The ends of thecarrier pins 68 remote from the flange 66 are connected to each other byan annular connecting member 182.

It will be understood that the output gear 78 functions as an outputshaft of the auxiliary transmission 14, which is selectively connectedto the input shaft 34 by means of the forward clutch 72 or the reversebrake 76.

Each planetary gear 60 is rotatable about an axis which is radiallyoutwardly of the axis of rotation of the corresponding planetary gear62. The planetary gear 60 meshes with the inner teeth of the ring gear58. The ring gear 58 is axially positioned while being sandwiched viawashers 184, 186 between the flange 66 of the carrier 70, and apositioning plate 188 which is secured to the second casing 74b. Thereverse brake 76 includes an annular anchor member 190 secured to thesecond casing 74b, a plurality of plates 192 supported by the anchormember 190, and a plurality of discs 194 supported by the ring gear 58.The plates 192 engage the inner circumferential surface of the anchormember 190 such that the plates 192 are rotated with the anchor member190 and are axially movable relative to the anchor member. The discs 194engage the outer circumferential surface of the ring gear 58 such thatthe discs 194 are rotated with the ring gear 58 and are axially movablerelative to the ring gear. The plates 192 and the discs 194 are arrangedalternately in the axial direction of the brake 76. A piston 198 isprovided for forcing the plates 192 and the discs 194 against eachother, to thereby prevent the ring gear 58 from rotating. The piston 198is slidably received within an annular cylinder bore 196 formed in thesecond casing 74b, and is biased by a return spring 199. The cylinderbore 196, piston 198 and return spring 199 constitute a major portion ofa hydraulic actuator for activating the reverse brake 76.

Each of the carrier pins 68 secured to the flange 66 of the carrier 70has a lubricant passage 202 which consists of an axially formedthrough-hole closed at its one end by a plug 200, and a radial holewhich is formed radially inwardly (toward the axis of the carrier 70)and which communicates with an axially middle portion of thethrough-hole. The lubricant passages 202 are provided to lubricate theinner and outer surfaces of the planetary gears 60, 62, extending fromone of the surfaces of the flange 66 on the side of the first gear 78,toward the gears 60, 62. Thus, the passages 202 communicate with thegears 60, 62.

The flange 66 of the carrier 70 has a generally annular lubricantreceiver 204 secured thereto in concentric relation with the carrier 70.This lubricant receiver 204 has a cylindrical portion 208, a conicalportion 210 extending from the cylindrical portion 208, and a ringportion 212 extending radially outwardly from one end of the conicalportion 210 remote from the cylindrical portion 208. The cylindricalportion 208 is disposed within a bore 206 formed through the fourthcasing 74d, such that a suitable gap is provided between the innercylindrical surface of the bore 108 and the outer surface of thecylindrical portion 106. The free end of the portion 208 remote from theconical portion 210 is located adjacent to the bearing 130. The conicalportion 210 has a diameter which increases in the axial direction awayfrom the cylindrical portion 208. The ring portion 212 is fixed at itsend to the surface of the flange 66 in which the lubricant passage 202is open. The fixed end of the ring portion 212 is located radiallyoutwardly of the open end of the lubricant passage 202.

While the axes of the input and output shafts 26, 34 of the CVT 12 andthe axes of the first, second and third gears 78, 80, 82 and the driveaxles 20 are all shown in FIG. 2 so as to lie in the same plane, foreasier understanding, it is to be understood that these axes areactually located as indicated in FIG. 4.

The present embodiment of the invention provides the followingadvantages:

In the illustrated embodiment constructed as described above, thehydraulic cylinder 52 for the second or output-side pulley 38 issupplied with the pressurized fluid through the fluid passage 176, whichis formed through the output shaft 34 of the CVT 12 (input shaft 34 ofthe auxiliary transmission 14) and the shaft portion of the first oroutput gear 78. In the presence of this fluid passage 176, the lubricantfor lubricating the auxiliary transmission 14, forward clutch 72 andreverse brake 76 is supplied to these elements, from outside the outputshaft 34 and the shaft portion of the first gear 78. As discussed above,the splined portion 148, connecting member 152, sun gear 56, bearing 174and bearing 126 are lubricated by the lubricant which is fed through thelubricant passage 164. The sun gear 56 and the associated elementsradially outward of the sun gear 56 are lubricated by the lubricantwhich is passed through the bearing 174. The forward clutch 72 islubricated by the lubricant which is discharged through the holes 175,177. Further, the planetary gears 60, 62 and the reverse brake 76 arelubricated by the lubricant directed thereto by means of the lubricantreceiver 204.

While the vehicle is running, the lubricant oil in the lower portion ofthe fourth chamber 96 is pumped up by rotation of the large-diametergear 84 with the differential casing 136, and delivered up to the thirdand second gears 82, 80. A relatively large portion of the lubricantmass reaching the gears 80, 82 is received by the circumferential wall144. Simultaneously, the lubricant mass which has once adhered to theouter teeth of the second gear 80 is transferred further to the firstgear 78 meshing with the second gear 80. Consequently, the lubricant isdischarged from the meshing teeth of the first and second gears 78, 80.As a result of this pumping action, the pressure of the lubricant aroundthe first gear 78 surrounded by the first and fourth casings 74a, 74d israised, whereby a portion of the lubricant around the first gear 78 isforced to be fed in the direction parallel to the axis of the first gear78. Consequently, the lubricant is fed through the bearing 130 and isdirected into the lubricant receiver 204. The lubricant which hasentered the receiver 204 is directed to the open end of the lubricantpassage 202 open in the surface of the flange 66 of the carrier 70. Thelubricant is delivered to the inner surfaces of the planetary gears 60,62 (on the side of the sun gear 56), through the lubricant passage 202.As a result, the inner surfaces of the needle bearings 180 and planetarygears 60, 62 are force-lubricated, whereby the durability of theauxiliary transmission 14 is improved. Generally, the gears of aplanetary gear mechanism must have a comparatively higher degree ofmeshing or engaging accuracy, than the gears of an ordinarytransmission, in order to assure smooth and noise-free transmission ofpower. That is, the meshing accuracy of the planetary gears 60, 62 andthe accuracy of supporting these gears must be kept at a sufficientlyhigh level. The lubrication system indicated above is effective tosatisfy this requirement. It is noted that the lubricant is fed by acentrifugal force away from the planetary gears 60, 62 in the radiallyoutward direction, whereby the ring gear 58 and the reverse brake 76 arelubricated.

In the present embodiment as described above, the lubricant stored inthe lower portion of the fourth chamber 96 while the vehicle is at restis pumped up toward the planetary gears 60, 62 for lubrication of thesegears. Therefore, it is not necessary to utilize a portion of thepressurized fluid produced by the hydraulic pump 54, as the lubricant tolubricate the gears 60, 62. This reduces the required amount of powerconsumption or required delivery capacity of the hydraulic pump 54.Thus, the pump 54 may be small-sized. Since the hydraulic pump 54 isdriven by the engine 8, the above arrangement contributes to animprovement in the fuel economy of the engine 8.

While the engine 8 is at rest, the carrier 70 and planetary gears 60, 62are rotated while the sun gear 56 is held stationary. In this condition,too, the lubricant is admitted into the lubricant receiver 204, and thegears 60, 62 are lubricated.

Referring to FIGS. 5 and 6, modified embodiments of the invention willbe described. The same reference numerals as used in FIGS. 1-4 will beused in FIGS. 5 and 6 to identify the functionally correspondingcomponents, and no redundant description of these components will not beprovided in the interest of brevity and simplification.

The embodiment of FIG. 5 uses a lubricant receiver 220 which has ashorter axial length than the lubricant receiver 204 and whose free endportion is not disposed within the bore 206. Namely, the free endportion of the lubricant receiver 220 has a larger diameter than thebore 206 and is located so as to surround the corresponding end portionof the bore 206, so that the lubricant discharged through the bore 206can be received by the receiver 220.

The embodiment of FIG. 6 uses a plurality of lubricant passages 222formed through the flange 66 of the carrier 70, in place of thelubricant passage 202 formed through each carrier pin 68 in thepreceding embodiments. In the present embodiment, the lubricant ispassed through the passages 222, toward the outer surfaces of theplanetary gears 60, the inner surface of the planetary gears 62, and theneedle bearings 180. However, the lubricant passages 222 may be providedin addition to the lubricant passages 202.

While the present invention has been described in its presentlypreferred embodiments with a certain degree of particularity, it is tobe understood that the invention is not limited to the details of theillustrated embodiments, but may be otherwise embodied.

In the illustrated embodiments, the lubricant passages 202 and/or 222are provided for all the planetary gears 60, 62. However, the passages202 and/or 222 may be provided for some of the planetary gears.

While the bearing 130 is provided between the gear portion of the firstgear 78 and the lubricant receiver 204 in the illustrated embodiments,the bearing 130 may be eliminated or replaced by other bearing means.

Although the lubricant receivers 204, 220 are secured to the flange 66of the carrier 70, these receivers may be secured to the fourth casing74d such that the end portion of the receivers is press-fitted in thebore 206. In this case, there exits a certain amount of gap between theflange 66 and the free end of the receivers 204, 220, but the gap doesnot cause a significant problem if the amount of the lubricant whichenters the receivers 204, 220 is sufficient.

While the auxiliary transmission 14 of the illustrated embodiments is adouble-pinion type, the present invention is applicable to a planetarygear mechanism of a single-pinion type, or a planetary gear mechanismwhich has two or more forward drive positions. Further, the invention isapplicable to a planetary gear transmission which includes two or moreplanetary gear mechanisms connected to each other.

Although the hydraulic pump 54 is driven by the engine 8 in theillustrated embodiments, a DC or AC motor may be used to operate asuitable hydraulic pump for operating the hydraulic cylinders 50, 52 ofthe CVT 12. In this case, too, the required power consumption of themotor is reduced because the planetary gears 60, 62 and the otherelements are lubricated by the lubricant not delivered from thehydraulic pump driven by the motor. Even if the planetary geartransmission does not use such a hydraulic pump, the present inventionprovides an advantage that the planetary gears may be suitablylubricated.

While the illustrated embodiments uses the single accumulator 110 whichis die-cast separately from the second casing 74b and secured to thevalve body 108, two or more accumulators may be used.

It is to be understood that the invention may be embodied with variousother changes, modifications and improvements which may occur to thoseskilled in the art, without departing from the spirit and scope of theinvention defined in the following claims.

What is claimed is:
 1. A planetary gear mechanism comprising:a rotatingshaft having a splined end portion; a sun gear splined at a free end ofsaid splined end portion, for rotation with said rotating shaft;planetary gears engaging said sun gear; a carrier for rotatablysupporting said planetary gears; a ring gear engaging said planetarygears; a clutch for connecting said rotating shaft and said carrier,said clutch including a first rotary member splined on said splined endportion of the rotating shaft, for rotation with said rotating shaftsuch that said first rotary member is adjacent to said sun gear at saidfree end, first friction means supported by and rotatable with saidfirst rotary member, a second rotary member rotatable with said carrier,and second friction means supported by and rotatable with said secondrotary member, said first and second friction means frictionallyengaging each other to transmit power therebetween; a housing in whichsaid rotating shaft, said sun gear, said planetary gears, said carrier,said ring gear and said clutch are accommodated, said housing rotatablysupporting said first rotary member in a substantially radially fixedposition for maintaining radial alignment of said first rotary memberwith a nominal axis of rotation of said rotating shaft; and said firstrotary member supporting said sun gear, and said first rotary member andsaid sun gear including means for maintaining coaxial relation with eachother, whereby said sun gear is maintained in said substantiallyradially fixed position.
 2. A planetary gear mechanism according toclaim 1, wherein said first rotary member includes a first annularextension which axially extends from one of opposite axial ends thereoftoward said sun gear, and said sun gear includes a second annularextension which axially extends from one of opposite axial ends thereoftoward said first rotary member, said first and second annularextensions axially slidably engaging each other.
 3. A planetary gearmechanism according to claim 1, wherein said first rotary member andsaid sun gear cooperate with said splined end portion of the rotatingshaft to define therebetween a radial clearance which extends axially ofsaid rotating shaft and whose amount is sufficient to permit a lubricantto flow therethrough.
 4. A planetary gear mechanism according to claim3, wherein said first rotary member and said sun gear fluid-tightlyengage each other.
 5. A planetary gear mechanism according to claim 3,further comprising a bearing interposed between said carrier and saidsun gear, said bearing being lubricated by the lubricant fed throughsaid radial clearance.
 6. A planetary gear mechanism according to claim1, wherein said first rotary member comprises a connecting membersplined on said splined end portion of said rotating shaft, and a clutchdrum secured to said connecting member for rotation therewith, saidfirst friction means being supported by said clutch drum.
 7. A planetarygear mechanism according to claim 6, wherein said housing has a borethrough which said rotating shaft extends said planetary gear mechanismfurther comprising a bearing interposed between a surface defining saidbore and an outer surface of said connecting member of said first rotarymember of said clutch.
 8. A planetary gear mechanism comprising:arotating shaft having a splined end portion; a sun gear splined at afree end of said splined end portion, for rotation with said rotatingshaft, said sun gear having an annular extension which axially extendsfrom one of opposite axial ends; planetary gears engaging said sun gear;a carrier for rotatably supporting said planetary gears; a ring gearengaging said planetary gears; a clutch for connecting said rotatingshaft and said carrier, said clutch including a first rotary membersplined on said splined end portion of the rotating shaft, for rotationwith said rotating shaft such that said first rotary member is adjacentto said sun gear at said free end, first friction means supported by androtatable with said first rotary member, a second rotary memberrotatable with said carrier, and second friction means supported by androtatable with said second rotary member, said first and second frictionmeans being frictionally engageable with each other to transmit powertherebetween, said first rotary member having an annular extension whichaxially extends from one of opposite axial ends thereof toward said sungear and which fluid-tightly engages said annular extension of said sungear, so as to maintain coaxial relation between said first rotarymember and said sun gear; a housing in which said rotating shaft, saidsun gear, said planetary gears, said carrier, said ring gear and saidclutch are accommodated, said housing rotatably supporting said firstrotary member; and said first rotary member and said sun gear whichfluid-tightly engage each other at said annular extensions thereofcooperate with said splined end portion of the rotating shaft to definetherebetween a radial clearance which extends axially of said rotatingshaft and whose size is sufficient to permit a lubricant to flowtherethrough, said annular extensions maintaining the coaxial relationbetween said first rotary member and said sun gear in spite of saidradial clearance.